Electric-arc lamp.



HA BECK. ELECTRIC AHC LMI/IPE APPLICATION FILD MILZII. IQI.

Patented Dee. 19, 1916.

UNITED sTATEs PATENT oEEIoE.

HEINRICH BECK, OF SCHENECTADY, NEW' YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORFORATION OF NEW YORK.

ELECTRIC-ARC LAMP.

Application filed Apr123, 1915.

To IZZ whom it may concern.'

Be it known that I, HEINRICH BECK, a subject of the Duke of Saxe-Meiningen, in the German Empire, residing at Schenectady, county' of Schenectady, State of New York, have invented certain new andV useful improvements in Electric-Arc Lamps, of which the followingr is a specification.

My invention has reference to improvements in electric are lamps, its object being to prevent the aceumulative ei'i'ect of the tendency of the electrodes, and especially of the anode, to side burning, by rectifying the side burning effect at itsinitial stage or at any time during its` profgress.

The invention is more particularly apM ilicable to are lamps with carbon or carbonaceous electrodes and its greatest utility is iiound in its application to arc lamps `for sea rcl. l i ghts.

In are lamps ot the kind indicated it has been iounfl that the' electrodes, and particularly the anode, is not being consumed evenly across its arcing end, but that the consumption is, generally', more vigorous on one side oit the electrode, whereby its -end becomes slanting and the are, and especially the crater, which in such electrodes is .the real source ot light, is obscured in a direction opposite the slant, thus diminislb,

ing the output of light. rThe causes of this side burning are manifold` one ot' them being the magnetic blow exerted upon the are by the conductors which carry the current to or from the electrodes. This blow effect is beingr more or less neutralized by a variety of devices which operate to produce a blow e'l'ect in a direction opposed to that produced by the ordinary conductors which cariv the current to or from the electrodes. These devices tend to keep the arc in its theoretical position, which in ease ot elec trodes that are in alinement with each other` is coincident with the axes of the electrodes. The devices herev spoken of are known in the art as blow magnets. rlhese may be permanent magnets or electroniaguets, or also current carrvingl eoiuluctors disposed about the arf' in a proper manner. ldf'hen the electrodes are in axial alinement and when the operatingr current is of moderate intensity, say up to 10, l2 or 15 amperes, biow magnet arrangements properly designed have proved to be successful in pre- Speeieaton of Letters Patent.

Patented Dee.. 19, 1916.

Serial NO. 23,349.

venting the side burning of the electrones. But when the electrodes are not quite in alinement or are decidedly inclined toward each other, as is the case in are lamps used -in searehlights, and particularly with the heavy currents used in searchlights, which freqiiently rise to 100 axnperes and sometimes reaeh as high a value as 200 amperes, blow magnets have not proved successful; and, in place of them or in addition to them, resort was had to the rotation of the electrodes about their own axes, whereby it was expected that the tendency to side burning would be shifted all around the circumference of the electrodes. In this manner the side burning has actually' been somewhat diminished; but it remains still serious enough to impede the uniform distribution of light from the crater of the anode.

By my invention side burning of the electrodes, and especially of the anode, is checked and etfaeed as soon as the tendency thereto manifests itself, and this can be done from momentto moment all throughout the trim, so that the anode is kept burning square from beginning to end, whereby the best possible distribution of light by means of a reflector or otherwise is secured.

Tn accordance with my invention, pantieularly as applied to searehlights, the electrodes are rotated, preferably by an electrievmotor, each about its axis, and are fed forward at approximately' the rate at which they are consumed, in the usual manner. The anode is usually in a substantially horizontal position with its arcintr end toward the reflector ot' the searehlight, and the cathode, facing the anode, is inclined toward the horizontal and usually with its rear end downwardly, and the axes of the two electrodes are in a substantially vertical plane.

Now, by reason of the inclination of one electrode toward the other, and by reason ot' the practical impossibility of making the electrodes absolutely straight-` and by reason oi the practical impossibility of rotating the electrodes strict-ly about their mathematical axes, and possibly also by reason of unequal density of the body of the eleotrode, side burning still takes place, and my invention provides means for discovering the tendency to side burning as'soon as its effect becomes at all perceptible. The

means consists ot' an optical arrangement whereby an nuage ot the arclng ends of the electrodiuuand ot' the arc between them is thrown upoiira' screen arranged within comfortable View of 'the attendant or operator. This image reveals the least tendency to side burningas soon as it appears. lt the anode'lurns sidewise-to the extent of two or three millimeters, this tact is at once shown by the image. in order to check the continued side burning and again make the electrode face square, l have found that it is only necessary to stop the rotation of the electrodes at the proper phase for a Jfew seconds, hardly ever more than ten seconds, although sometimes three or four seconds stoppage is sufficient After this has been done the rotation o'lthe electrodes is again resumed until another tend- -ency 'tofside burning is revealed by the ilnageon the screen, when the rotation ot the electrodes is again stopped for a few seconds; and this is repeated as often as the side burning tendency is shown. this manner the crater in the anode is main- '.tained Very symmetrical, and extends from as 'follower Figure l is a side elevation ot theelec- 'odes of a searchlight lamp showing part of the mechanism for rotating the elect1'odes;-l `ig. Q is a side elevation of the electrodes indicating" the etlicct of the 'side burning` and also the position to which the anode is brought to elace the tide burning; Fig. 3 isa front end elevation' of a searchlight equipped with my improvement with the shutters partly broken away and a portion of the casing; in section; and Fig. 4 is a side elevation of a searchlightcasing with. a portion broken away and equipped. with my improvement.

L Like numerals of reference indicate like parts all throughout the drawing.

The electrodes 1*? pass loosely each through a boss 3 and are additionally guided by the ,Qjrooved rollers 4 and are rotated either by hand or by an electric motor 4.', through the intermediary of the cog gearings rlhis, as Well as the means for feeding the electrodes, is a common' arrangement and need not be described in further detail.; IThe anode l is intended to he substantially horizontal and the cathode 2 'is inclinedthereto at ai: angle ot' about Laconic lio, with its rear end downwardly and with its anfing end at a distance of about 22 millimeters Afrom the lace of the anode. The inclination of the cathode and the distance of the same from the face of the anode are so chosen with reference to the diameter of the anode that with the arrangement of the electrodes indicated the arc extends from the cathode inan upward curw toward and to the anode, playing mainly upon the upper halt of the face of the anode and just touching the upper edge of the same.. 'l` he particular angle of inclination ot' the cathode and the distance from each other of the electrodes abete indicated linils the conditions of my invention when the diameter ot the anode is about 16 millimeters. lVhen the diameter oit the anode is diii'erent, then the inclination ot the' cathode ano the distance between the faces of the electrodes will be chaiiged so as to bring about the result aimed at by this arrangement, namely, the playing ot' the are mainly upon the upper half ofthe Iend face of the anode and just touching` the upper edge of the same. This arrangement of the electrodes is important for the suc c essiul operation of my invent-ion. ln l the arcing end of the anode is shown square, that is to say, about at right angles to the axis of the electrode and the crater of the anode is indicated. in dotted lines as symmetrical with reference to the body of the electrode and with its outer Haring mouth merging with the cylindrical surface of the electrode and forming with it sharp knife edge. This is `the manner ,in 'which the anode burns when it is controlled. accordance with my inrenfi lt will be noticed thi sented in the dra ring; u' bend is shown boldly am` l 4 ,gc-,rated to indicate that the electrodes are not i enerally perfectly straigh i. so that when the electrode is rotated one side ot its free end describes a smaller circle than the other. The same thing would happen it the electrodes were perfectly straight but did not pass through the boss or holder 3 with its axis coincident with that of the holder, but formed an angle with it, This is rcallypractically unavoidable; it aluY 'as happens and so do bends in the electr l more or less pronounced happen, and these general and unavoidable conditions are intended to be indicated by the bold bend ,of the portion of the holder and it 'will be seen that when 'the anode is rotated about this axis that partl ot the face et the electrode. whichis on the acerca et the been? will desarme 'it e `be a reversed one.

smaller circle than the part of the end face which is next to the concave side of the bend. In consequence of this the part of the end face of the anode which is next to the convex side of the bend will be exposed to the action of the arc a longer time during each period of revolution than the diametrically opposite side of the electrode face. The result of this is that the anode does not burn off square. This would be true even if the arc passed in a straight line between the eleetrodes; but, as a matter of fact, with the arrangement of the electrodes here shown and described the a'rc does not so pass, but curves upwardly as indicated; and this arrangement, while on the one hand it tends to intensify the side burning, as will be readily understood, it is, on the othe hand an' important factor inthe process of rectifying the side burning, as will presently appear. The effect of the arrangement de scribed is that the arc, eating'into the faceof the anode acts upon the same like a chisel to which the proper inclination is given upon the face of a metal rod rotated in a lathe; it drills, so to speak, a cavity into the face of thellanode, the mouth of said cavity ('called thecrater) being -equal to the diameter of the anode, so that'the crater merges with the cylindrical surface of the anode, forming there with the same a sharp knife-edge. The consequence of'this formation is to still further promote the tendency to side burning because only very little material has to be burned away at any part of the crater edge to make this edge slanting instead of square.'

In accordance with my invention means are provided for detecting the side burning effect as soon as it is at all perceptible, as indicated in* Figs. 3 and 4. A short tube 7 projects from the casing 8 of the scarchlight and the outer end ot' the tube is closed by a disk of ground or opalized glass 9. A system of mirrors or lenses or both is disposed within the casing in such manner as to project the image of the ends of the electrodes and of the arc between them upon the glass disk. As here shown there are two mirrors 10 and 1l and a condensing lens 12 between them so arranged that the image projected on the screen 9 would be a reversed image, as indicated at l', 2', in Fig. 4; but the optical arrangement may be 'different from that indicated and it is not necessary that the image The opera-tor or attendant standingat the side of' the searchlight has the image ot' thel electrodes clearly in view. He sees these electrodes rotating, he sees the play of the arc between them, and sees'v clearly the cfect of side burning when such occurs, in the manner indicated in Fig.

4, on the face 4of the ground or opalized glass screen.

As soon as side burning is observed the operator, in accordance with my invention, stops the motor, if such is used, by which the electrodes are rotated, by a key or switch 13, and he so times the stoppage that the side burned portion i4 of the anode comes below the active region of the arc, while the projecting lip 15 of the electrode, which is just oposite the side burned portion, stands with in the region of the upwardly curved are, as indicated in Figs. 2 and 4. This can be easily done, since the electrodes are lrotated at a slow rate, about thirteen times per min ute. When this has been d'one, the lip 15 and the portion immediately below it, embracing only a small amount of anodev terial, burn away rapidly and in a few seconds the anode is again squared, after which the rotation of the electrodes is again\ started.

In the' manner hereinbefore described the side burning of the anode can be checked instantly as soon as the least tendency thereto is observed, and the side burning which has occurred can be el'aced in a Afew seconds, so thatithe anode canlbemaintained with its end face perfectly square, and the light from the crater can, therefore, issue on all sides throughout a whole trim,

What I claim as new and desire to secure by Letters Patent of the United States, is zl. The method of checking and efacing the side burning of the anode of an are lamp, which consists in directing the arc from the cathode at such an acute angle .upwardly against the upper portion of the face of the anode as to just touch. its upper edge and rotating the anode about its axis, observing the effect of side burning at its initial stage, stopping the rotation of the anode with the side burned portion outside the region of the are until the anode f'ace is squared.l and then continuing the rotation of the anode.

Q. The method of checking and effacing the side burning of the anode of an arc lamp, which consists in so directing the arc from the cathode ccccnl'rically against the face of the anode as to just touch the edge 'of the latter and rotating -the anode about its axis,

observing the ellect of side burning at its` HEINRICH BECK.

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